Selective printing assembly having printing surfaces at different levels



y 9, 1967 A. K. BOYD 3,318,430

SELECTIVE PRINTING ASSEMBLY HAVING PRINTING SURFACES AT DIFFERENT LEVELS 3 Sheets-Sheet 1 Filed Oct. 11, 1965 M 0 B K d e r H A BY E. Vmhmy ATTORNEY y 9, 1967 A. K. BOYD 3,318,430

SELECTIVE PRINTING ASSEMBLY HAVING PRINTING SURFACES AT DIFFERENT LEVELS Filed Oct. 11, 1965 3 Sheets-Sheet 2 May 9, 1967 A. K. BOYD SELECTIVE PRINTING ASSEMBLY HAVING PRINTING SURFACES AT DIFFERENT LEVELS 3 Sheets-$heet 5 Filed Oct. 11, 1965 I CAM-GEAR WHEEL 38 2 3 4 5 6 7 8 9 IOII l2l3|4|5|6|7|8|9202|22232425 l 2 3 4 5 6 7 8 9 m H m M 5 Wm H m w m 2 mwI HZEQ ATTORNEY United States Patent Office 3,318,430 Patented May 9, 1967 3,318,430 SELECTIVE PRINTING ASSEMBLY HAVING PRINTING SURFACES AT DIFFERENT LEVELS Alfred K. Boyd, Houston, Tex., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Filed Oct. 11, I965, Ser. No. 494,509 7 Claims. (Cl. 197-48) This invention relates to printing devices and more particularly to a printing head assembly for a strip chart printing recorder.

One advantage of such a recorder is that it is capable of making a printed record of a number of variables on a strip of recording paper. It is, of course, necessary to identify the separate variables being recorded. This may be accomplished by utilizing a print wheel with recording dots and numbers so spaced that a number is printed every time a dot is printed, the number identifying the particular variable being recorded. When there is very little change in position on the chart between the separate recordations, successive numbers indicating the variables may be printed in blurred overlapping relation. It is therefore desirable that the identifying number for each variable be printed periodically rather than with each recording.

Accordingly, it is one object of the invention to produce a device capable of selectively printing a dot or a dot and a number.

It is another object of the invention to produce a printing device capable of systematically recording a plurality of variables and the indication of the variables recorded.

Other objects and features of the invention will bei come more readily understood from the following detailed description and appended claims when read in conjunction with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof, and in which;

FIGURE 1 is a pictorial view of a print wheel according to the present invention.

FIGURE 2 is a cross-section view of a portion of the print wheel shown in FIGURE 1 taken along section line 22.

FIGURE 3 shows a portion of a multi-record strip chart printed with a numeral identifying each dot.

FIGURE 4 shows a portion of a multi-record strip chart printed with the device of the present invention wherein numbers indicating variables are only printed periodically.

FIGURE 5 is an elevational view of one embodiment of the device of the invention set to print dots consecutively and numbers periodically.

FIGURE 6 is an elevational view of the same embodiment of the invention set to print only dots.

FIGURE 7 is an elevational view of the same embodiment of the invention set' to print dots and digits each time.

FIGURE 8 is a cross-sectional view taken along section line 8-8 of FIGURE 7.

FIGURE 9 is a chart showing the printing sequence of numerals and dots when the printing wheel is set to print numbers once each 25 cycles.

Referring now to FIGURES l and 2, a print wheel It is shown which comprises a plurality of raised numbers 11 with an equal number of corresponding raised dots 12. The structure of the print wheel may best be understood with reference to FIGURE 2 in which the difference in height between the raised dot 12 and the raised number 11 may be clearly seen. In one embodiment, the print wheel is comprised of an inner solid wheel 14 and a concentric ring 15 overlying the inner wheel 14. Ring 15 may be, for example, of vulcanized rubber, since vulcanized rubber may be molded easily into the desired shape and provides a firm contact between wheel 14 and ring 15. A suitable difference in height of the numeral portion 12 and the clot portion 11 may be, for example, 0.015 inch. This height difference allows a dot to be printed during the printing impact without the simultaneous printing of a numeral, because, as explained hereinafter, a spacing arm interposed between a cam Wheel and the printing surface of the print wheel provides a clearance between the number on the wheel and the recording chart when a dot only is to be printed and no clearance when both dot and numeral are to be printed. The printing impact is normally accomplished by a depressor bar depressing the entire printing assembly as will be explained hereinafter. The correct spacing can be easily achieved by a spacing cam that has a greater effective radius than the height'of the number 11 but less than the height of the dot 12. This allows the dot to engage the paper during the printing impact but not the number.

The portion of the strip chart shown in FIGURE 3 illustrates the record obtained when both a dot and a numher are printed during each recordation. The portion of the strip chart shown in FIGURE 4 illustrates the record which is produced using the device according to the invention. As may be seen in FIGURE 4, to have the identifying number, indicating the variable being'recorded, printed periodically is extremely desirable when the dots are very close together. Although FIGURES 3 and 4 only illustrate a four-variable recording, the illustration is not to be construed in a limiting sense. By proper arrangement, any number of variables may be recorded, for example, an arrangement for a print wheel having 24 nu'm bers is shown in FIGURE 1 and to be further described below in conjunction with the mechanism that drives it.

One embodiment capable of accomplishing the syste matic periodic printing is shown by the printing head assembly illustrated in FIGURES 5 and 8. This printing head assembly is to be used in conjunction with a multi record strip chart recorder of the type having a synchronous motor drive, means for positioning and indexing a print head assembly, a depressor bar, a carriage embody ing said printing head assembly, and means for advancing and positioning the strip chart. Such a recorder is de scribed in Process Instruments and Controls Handbook, Douglas and Considine, McGraw-Hill Book Company, 1957, pages 816 through 8-18.

The operation of the printing head mechanism is best understood with reference to FIGURES 5 and 8. In FIGURE 8 the printing head assembly is shown mounted on frame 40 Whichpivots about shaft 16. On shaft 16 is a Geneva pin wheel 19 which turns a four-slot Geneva gear 18. A Geneva gear system is used to convert continuous rotational motion to intermittent rotational motion. In the embodiment shown, shaft 16 is continuously rotating. It is necessary that the rotation of the print wheel be intermittent so that during the actual printing operation, the print wheel will not be rotating, being at a standstill and allowing a number and/or dot to be printed, as explained below. The rotary motion of the four-slot Geneva gear 18 is transferred by shaft 20 to an eight-tooth gear 17. Gear 17 is coupled to drive gear 22 mounted on shaft 23. On shaft 23 is the inking wheel 21 which is driven by gear 22, using a key-in-slot coupling 35. Gear 22 is driven by gear 18 through 360/n", n referring here and throughout the specification to the number of raised numbers on the print wheel, n being 24 in the disclosed embodiment of the invention. Gear 22 engages and drives gear wheel 33 and spacing cam gear 24 mounted on shaft 29. Print wheel 10 (similar to the 53 one shown in FIGURE 1) is driven by gear 33 using a key-in-slot coupling 34.

Spacing cam gear wheel 24 is used in conjunction with arm 26 (FIGURE 5) to prevent the printing of a number with every recordation. Spacing cam gear wheel 24 has a spacing shoulder 38 with an indentation 25 on its periphery. Spacing arm 26 is held against spacing shoulder 38 by spring 27, arm 26 being pivotally mounted on pin 39. The dimensions of spacing shoulder 38 and spacing arm 26 are such that when the spacing shoulder and the spacing arm are in the position shown in FIGURE 5, only dots will be printed when the print head engages the paper on roll 37. This is due to the fact that the dot height is greater than the number height, as shown in FIGURE 2. Spacing arm 26 extends so that its point of impact on the paper roll 37 is slightly behind the point of impact of the dot 12. This is to prevent the impact area on arm 26 from coming in contact with ink deposited from previous recordations. When indentation 25 on shoulder 38 is positioned above spacing arm 26 so that spacing arm 26 enters the indentation 25, both a dot 12 and a number 11 will be printed since the print wheel is permitted to come closer to paper roll 37 due to spacing arm 26 entering the indentation 25, compressing the dot 12 enough to permit a number to be printed. For correct operation, indentation 25 should extend over an arc of on the circumference of shoulder 38.

When it is desired to print dots only, clamping screw 32 is loosened and wedge shaped member 31 is rotated around so that the outer edge of member 31 corresponds with indentation 25, as particularly illustrated in FIG- URE 6. This will prevent spacing arm 26 from entering indentation 25, allowing the print wheel 19 to come close enough to the paper to print only a dot. On the other hand, if numbers and dots are to be printed at all times, spacing arm 26 is lowered to the position shown in FIG- URE 7, so that the print wheel 10 may be lowered and come in contact with the paper roll 37 without limitation, thus printing both numbers and dots with 'each recordation. The entire print head assembly rotates about shaft 16 because of the motion of drive rod 28 shown in FIGURE 5. The printing motion is as indicated by the double headed arrow in FIGURE 5.

Correct gear ratios between the various gears shown and the spacing cam wheel 24 are essential to achieve the systematic, periodic printing. The operation of the embodiment will be further explained with respect to a print wheel 10 having 24 pairs of dots and numbers, as shown in FIGURE 1. In this case, the gear ratio between gear wheel 22 and spacing cam gear 24 is 24:25 or run-+1, the gear wheel 22 having, for example, 48 teeth and cam gear 24 having 50 teeth. As mentioned above, gear wheel 22 is rotated through 360/ n or through between recordations for 24 numbers. Because of the direct coupling 34, gear wheel 33 and print wheel 1% are also rotated through 15. The print wheel 10 is thus rotated through 24 arcs of 15 each for one complete revolution. However, during this time, spacing cam gear wheel 24 will have rotated only through /35I flS of a complete revolution. If indentation 25 were positioned above spacing arm 26 on the first recordation so that the number 1, for example, is allowed to be printed, then 25 recordations (one complete revolution) later it will again be in the correct position for printing. During that time the print wheel 10 will have advanced through 25 arcs of 15 each. Since it takes only 24 arcs to complete a revolution, print wheel 10 will then have made one complete revolution plus one arc. Due to the fact that a rotation through 24 arcs brings the print wheel to the number 1, a complete rotation plus one are will bring the print wheel around to the number 2. Therefore, with a rotation through 25 arcs, the number 2 will be in a position to be printed. In a similar manner, after the print wheel 10' has advanced through 25 more positions, the indentation 25 will have made one revolution and the print wheel will have made one revolution plus one position, placing indentation 25 opposite the number 3 so that a 3 will be printed. In this manner, the desired systematic periodic printing of a numeral is achieved.

The rotation of the print wheel 10 and the cam gear wheel 38 are shown in graphic form in FIGURE 9. Every shaded square in said figure designates that a number and a dot is printed. The blank square represents a dot only being printed. The vertical axis represents the circumference of the print wheel 10 and the horizontal axis the circumference of the cam gear wheel 38. It should be noted that the print wheel circumference is divided into 24 divisions, representing the number of positions, or 24'positions of 15 each rotated during a complete revolution of the wheel. Since the print wheel completes a revolution in one less increment than the cam gear wheel, the slot in the cam gear wheelrwill change one position with each rotation. Thus it may be observed that although a dot is printed for each 15 increment of rotation of the print wheel, a number is printed for each complete revolution of the print wheel plus one increment. A l is therefore printed only at every 25th dot of the variable indicated by the 1. This is shown in simplified form in FIGURE 4 where a 1 is only printed every fourth dot. In relation to the total number of dots printed for a 24 number print wheel, a 1 is printed every 625th dot.

Ink wheel 21 may be covered with an ink soaked felt for inking the numbers and dots as they rotate and come into contact with the felt. However, if it is desirable that each variable be of a different color, the periphery of ink wheel 21 may be divided into .24 slots, each slot having felt soaked with an ink of a different color. Since ink wheel 21 and the print wheel 10 are driven at the same speed, the same number and dot would fall into the same color during each revolution. Therefore, each number would always be printed in the same color.

Although the present invention has been shown and illustrated in terms of specific preferred embodiments, it will be apparent that changes and modifications are possible without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A print mechanism for recording a plurality of channels of information on a strip of paper, comprising in combination, a print wheel having a series of raised dots and a series of raised numerals around the periphery of said wheel, a cam wheel having an indentation on its periphery for controlling the spacing between said print wheel and said strip of paper, drive means for rotating said print wheel and said cam wheel and periodically engaging said print wheel with said strip of paper, spacing means for engaging said cam wheel to limit the travel of said print wheel to a first position while printing a dot when said spacing means is on the periphery of said cam wheel, and enabling said print wheel to travel to a second position for printing a dot and a number when said spacing means is in said indentation on said cam wheel.

2. Means for periodically printing numerical designations for a plurality of variables on a strip chart, comprising in combination, a print wheel having a series of raised dots and a series of raised numerals around the periphery of said wheel, said dots having a greater height than said numerals, a cam wheel having an indentation on its periphery for controlling the spacing between said print wheel and said stri chart, and a spacing arm interposed between said cam wheel and said strip chart, said spacing arm engaging said cam wheel either in or out of the said indentation so as to selectively vary the spacing between said print wheel and said strip chart, thereby selectively printing either a dot and a dot.

3. Means for periodically printing numeral designations for a plurality of variables on a strip of paper, comprising in combination, a print wheel having a series of raised dots and a series of raised numerals around the periphery thereof, said dots having a greater height than said numerals, a cam wheel having an indentation on its periphery for controlling the spacing between said print Wheel and said strip of paper, and a spacing arm engaging the periphery of said cam wheel and the indentation thereon, whereby a dot is printed on a strip of paper when said spacing arm is on the periphery of said cam wheel and a dot and a number is printed on said strip of paper when said spacing arm is in the indentation on said cam wheel.

4. A print mechanism for recording a plurality of channels of information on a recording medium, comprising in combination, a print wheel having a series of raised dots and a series of raised numerals around the periphery thereof, a cam wheel having an indentation on its periphery for controlling the spacing between said print wheel and said recording medium, drive means for rotating said print wheel and said cam wheel, and spacing means for engaging said cam wheel to limit the travel of said print wheel to a first position when said spacing means is On the periphery of said cam wheel thereby enabling said print wheel to record a dot on said recording medium, and to limit the travel of said print wheel to a second position, when said spacing means is in said indentation on said cam wheel thereby enabling said print wheel to record a dot and a number on said recording medium.

5. A printing head assembly for a strip chart recorder, comprising in combination, a shaft, a print wheel mounted on said shaft, said print wheel having a first row of raised numbers spaced around the rim of said wheel and a row of raised dots spaced around said wheel so that a dot corresponds to each number, said dots being raised about 0.015 inch higher than said numbers, a spacing cam having a width greater than said raised numbers but less than said raised dots, a cam .wheel having an indentation on its circumference such that when said spacing cam is in line with said indentation said print wheel is enabled to travel to a second position, whereby both a dot and a number are printed, and when said spacing cam is not in line with said indentation, the travel of said print wheel is limited to a first position, and a dot only is printed, and means 'for rotating and holding in position said print wheel and said spacing cam.

a number or only 6. A printing head assembly as defined in claim 5 wherein said means for rotating and holding in position said print wheel and said spacing cam comprises a first gear wheel mounted on said shaft adjacent said print wheel and coupled with said print wheel, a second gear wheel mounted on said shaft and adjacent to and coupled with said cam wheel, and a drive gear wheel engaging said first and second gears, the gear ratio between said first gear and said drive wheel being 1:1 and the gear ratio between said second gear and said drive gear being n+1:1 where n 'is the number of said raised numbers on said print wheel.

7. A printing head assembly for printing on a strip of paper of a multi-record strip chart recorder, comprising in combination (a) a print wheel having a row of raised numerals and a roW of raised dots on its rim, said dots being raised higher than said numerals;

(b) a cam wheel having an indentation on its rim;

(0) a first shaft having said print wheel and said cam wheel mounted thereon;

(d) a drive gear mounted on a second shaft, said drive gear engaging and turning said print wheel at a ratio of 1:1 and said cam Wheel at a ratio of n:n+1, Where n is the number of numerals on said print wheel;

(e) an ink wheel mounted on said second shaft driven by said drive gear and engaging said print wheel to ink said dots and numerals thereon;

(f) a drive system engaging said drive gear and turning said gear periodically through It arcs of 360/12 degrees for each rotation of said print wheel; and

(g) a depressor bar for engaging said print wheel and said strip of paper to print a number and a dot on said strip of paper when said indentation on said cam Wheel is adjacent the number being printed, and printing only a dot when said indentation is not adjacent the number being printed.

References Cited by the Examiner UNITED STATES PATENTS 2,502,491 4/1950 Thompson 197-49 X 2,561,476 7/ l Lang. 2,993,642 7/1961- Fender et a1 l3 37 3,034,782 5/1962 Weidenhammer 197-49 X 3,205,305 9/1965 Clark et a1. 10 l48 X 3,223,033 12/1965 Sundblad 101-368 ROBERT E. PULFREY, Pr mary Examiner. E. S. BURR, Assistant Examiner. 

1. A PRINT MECHANISM FOR RECORDING A PLURALITY OF CHANNELS OF INFORMATION ON A STRIP OF PAPER, COMPRISING IN COMBINATION, A PRINT WHEEL HAVING A SERIES OF RAISED DOTS AND A SERIES OF RAISED NUMERALS AROUND THE PERIPHERY OF SAID WHEEL, A CAM WHEEL HAVING AN INDENTATION ON ITS PERIPHERY FOR CONTROLLING THE SPACING BETWEEN SAID PRINT WHEEL AND SAID STRIP OF PAPER, DRIVE MEANS FOR ROTATING SAID PRINT WHEEL AND SAID CAM WHEEL AND PERIODICALLY ENGAGING SAID PRINT WHEEL WITH SAID STRIP OF PAPER, SPACING 